Fix engine-wide code review findings

Collisions: init bucket heads to -1 (QueryAabb hung before the first
rebuild), reset query stamps on truncated QueryAabb (later queries
silently dropped entities), inside-origin raycasts hit at fraction 0 for
circles too, exactly-touching boxes now pair like touching circles.

Graphics: render into the letterbox viewport so the picture matches
ScreenToWorld/WorldToScreen instead of stretching; Y-sort by the
transform pivot rather than the quad center; lock-free snapshot
LayerRegistry (parallel submit read it unsynchronized); validate
InitialCapacity; warn when UseRenderer2D drops options of a later scene.

Core: scenes are explicitly single-use (re-loading threw silently
duplicated systems/entities before — now it throws), Scene.RegisterUnload
for per-scene resources, a switch requested during the reveal phase
covers again instead of hard-swapping, borderless fullscreen
(HardwareModeSwitch off), InputCapture service for input-suppressing
overlays, host disposes the transition renderer and IDisposable services
on shutdown.

Input: game input reads as released while InputCapture is held; mouse
position and wheel freeze so deltas stay zero.

DevConsole: holds InputCapture while open (typing no longer drives the
camera), Revision increments only under the lock, quoted command
arguments, history capped at 256.

UI: scene Desktop skips Myra input processing while the console is open
(clicks no longer fall through), is disposed on scene unload, and Myra
init no longer depends on a process-static flag.

Audio: validate channel count/sample rate before stopping the previous
track, empty looped oggs no longer hang FillBuffers, the instance stops
when a non-looping track drains (IsPlaying was stuck true).

Atlases: metadata v2 stores per-source size+mtime snapshots, so
timestamp-preserving copies and renames invalidate correctly; loader
checks the version and disposes pages on partial load failure; shared
pages never exceed a non-POT MaxPageSize; oversized items pack first
onto exact-size pages instead of splitting an open shared page; the CLI
validates numeric options.

Assets.Generator: file names are escaped in XML docs and string
literals, members no longer collide with the enclosing class (CS0542),
and the Assets root is resolved against build_property.projectdir so
nested "Assets" directories do not shift region paths.

Pathfinding: queries throw when the grid was resized after construction;
generation stamps survive int overflow.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/MrGameEng.Atlases.Tests/AtlasBuilderTests.cs

@@ -151,6 +151,39 @@ public sealed class AtlasBuilderTests : IDisposable
         Assert.True(Assert.Single(result.Groups).PageCount >= 3);
     }
 
+    [Fact]
+    public void Build_ContentChangedWithSameTimestamp_Rebuilds()
+    {
+        WritePng("UI/button.png", 8, 8, 1, 2, 3);
+        AtlasBuilder.Build(Options());
+
+        // Копия «с сохранением времени» (robocopy, zip): mtime прежний, контент другой.
+        var path = Path.Combine(SourceDir, "UI/button.png");
+        var timestamp = File.GetLastWriteTimeUtc(path);
+        WritePng("UI/button.png", 16, 16, 9, 9, 9);
+        File.SetLastWriteTimeUtc(path, timestamp);
+
+        var result = AtlasBuilder.Build(Options());
+
+        Assert.False(Assert.Single(result.Groups).Skipped);
+    }
+
+    [Fact]
+    public void Build_OldMetadataVersion_Rebuilds()
+    {
+        WritePng("UI/button.png", 8, 8, 1, 2, 3);
+        AtlasBuilder.Build(Options());
+
+        var metadataPath = Path.Combine(OutputDir, "UI.atlas");
+        var json = File.ReadAllText(metadataPath)
+            .Replace($"\"version\": {AtlasMetadata.CurrentVersion}", "\"version\": 1");
+        File.WriteAllText(metadataPath, json);
+
+        var result = AtlasBuilder.Build(Options());
+
+        Assert.False(Assert.Single(result.Groups).Skipped);
+    }
+
     [Fact]
     public void Metadata_JsonRoundtrip_PreservesEverything()
     {